Luiart,
This VI measures the frequency of a repeating square wave using two counters. The chosen counter counts rising edges of the square wave. The gating counter controls or gates the chosen counter for a specified interval.
The source and gate controls allow the user to conveniently select from PFI lines, Internal Timebases, RTSI lines, and Miscellaneous (like other counters) for source and gate origins. For instance, if you select Internal Timebase, 20 MHz in the Source Specification and if you select a default PFI Line in the Gate Selection , a Timebase signal of 20MHz will be used as the source of the counter and the gate will come from the default PFI line. Now, regarding measure specs, all they do is set up the delay and the pulse duration
for the pulse generated in counter-1.
To see more detailed information, you can go to the LabView Contents and Index and search for Counter Set Attribute.
